Vitamin D Dependent Calcium Binding Protein in Rat Intestinal Mucosa

Abstract

The purification and properties of vitamin D dependent calcium binding proteins were studied in rat intestinal mucosa. Two different vitamin D de pendent calcium binding proteins were fractionated by the DEAE-cellulose column chromatography.Their properties were analyzed with the polyacryl amide gel disc electrophoresis and the sucrose density gradient ultracentrifuga tion. One of them is having a molecular weight about 24,000 representing rapid migration on acrylamide gel electrophoresis and seems similar to the calcium binding protein obtained from chick intestinal mucosa in respect of its size and electrophoretic mobility. The other protein is a larger molecule (mol. wt. 145,000) which is eluted in first fraction from DEAE cellulose chromatogra phy. The smaller molecule of binding protein associates with one atom of calcium per one molecule of protein and the larger molecule would associate with more than 2 atoms of calcium.

Demonstration of two different vitamin D-dependent calcium-binding proteins in rat intestinal mucosa.

“…The second CaBP is not found in vitamin D-deficient animals, but can be induced 251 by readministration of vitamin D. Most investigators have demonstrated that the molecular weight of this vitamin D-dependent CaBP is in the range of 8,000 -13,000 (3,4). However, OOIZUMI et al (2), using different techniques for frac tionation and 45Ca binding assay, obtained a molecular weight of 24,000 for this protein. This protein was obtained from the mucosa of the entire small intestine 16hr after the administration of 2,000 IU of vitamin D3 and was assayed for 45Ca binding activity on 45Ca-equilibrated Sephadex G-25 columns .…”

“…A protein of mini mum molecular weight of 100,000 was present in all sections of the small intestine and was found in both vitamin D-deficient and repleted rats, and appears to correspond to the large CaBP (molecular weight 145,000) obtained by OOIZUMI et al (2) who used 45Ca-equilibrated Sephadex G-25 column in their assays. A vitamin D-dependent CaBP, molecular weight 27,000, was found predominantly in the jejunum and ileum and appears to correspond to the protein with a mole cular weight of 24,000 which was isolated from the entire small intestine by OO IZUMI et al (2). DRESCHER et al (3) and HITCHMAN and HARRISON (4), however, were unable to demonstrate this protein.…”

“…Since the discovery of a vitamin D-dependent calcium-binding protein (CaBP) in chick duodenal mucosa (1), similar proteins with calcium binding properties have been detected in the intestinal mucosa of several species, viz, rat (2)(3)(4), hu man (4)(5), dog (6), monkey, calf (7) and pig (4). At the present time, CaBP is thought to be one of the important factors for the intestinal Ca-transport process regulated by vitamin D (8).…”

Development of 1,25-dihydroxycholecalciferol receptor in the duodenal cytosol of chick embryo.

“…CaBP, which is thought to be related to the vitamin D-dependent translocation of calcium, was identified in the intestinal mucosa of chick Taylor, 1966 and1968) and several mammalian (Ooizumi et al, 1970;Wasserman and Taylor, 1970;Menczel, 1971;Sands and Kessler, 1971). However, it cannot be detected in the intestine of embryonic chick.…”

Vitamin D3 Action on RNA Synthesis in Rat Intestinal Mucosa

“…In our laboratory, Moriuchi et al have demonstrated the evidences that 3H-vitamin D3 was found inside nuclei in rat intestinal mucosa with the electronmicroscopic radioauto graphy (4). Calcium-binding protein was puri fied by Wasserman and Taylor (5) in chick intestinal mucosa and also in the rat by Moriuchi (6) and Ooizumi (7). This protein is hardly found in rachitic rat, and the presence of two kinds of the protein in vitamin D3 treated rats suggests that it may have been induced by vitamin D3 (7).…”